It is known in the art to provide integrated semiconductor elements in which relatively tiny but complex logic and/or control devices and circuits are integrated on the same semiconductor chip with very much larger power devices previously only available in separate discrete form. As used herein, the words "smart-power" are intended to refer to such integrated, single chip, combined logic/control plus power device functions.
Integration of logic/control and power device functions on the same chip places more stringent and different demands upon the structure and the fabrication process than where those elements are provided in separate chips. For example, the location of and means for forming the various P and/or N regions in the chip must take into account the frequently conflicting requirements of the logic/control circuits and the power devices.
In many smart-power devices it is desired to be able to provide a charge pump, that is, a means for providing internally a voltage which is above the supply voltage or not readily derived from the supply voltage by the usual voltage dividers. In the prior art this has been accomplished by using a transistor connected as a diode in a voltage doubler circuit. However, this approach suffers from a number of limitations well known in the art. It has been found that improved devices may be prepared by using an integrated Schottky diode for this function.
At the same time, a Schottky diode may also be used in smart-power devices as a clamp diode or charge pump rectifier or as an improved Kelvin voltage sense contact to the collector region of a bipolar transistor to provide improved clamping of the emitter-base voltage.
Accordingly it is an object of the present invention to provide a means and method for an improved integrated Schottky diode which is particularly convenient for use in smart-power devices.
It is a further object of the present invention to provide a means and method for an improved integrated Schottky diode which is suitable for use as a charge pump diode.
It is an additional object of the present invention to provide a means and method for an improved integrated Schottky diode which is suitable for use as a Kelvin contact to the collector of an integrated bipolar transistor.
It is an further object of the present invention to provide the foregoing using a structure and process which is compatible with the other structure and process requirements for forming smart-power type devices.